Kathmandu , Nepal -LRB- CNN -RRB- -- The two-day ritual slaughter of tens of thousands of animals -- among the world 's largest sacrifice of animals -- began Tuesday in southern Nepal , officials said .

About 200,000 animals , including male water buffalo , goats and roosters will be slaughtered , despite protests from animal rights activists , according to the chief priest of the festival .

People from Nepal and India sacrifice animals to the goddess Gadhimai in the Bara district , about 150 kilometers -LRB- about one mile -RRB- south of Kathmandu , in thanks for wishes granted .

`` This is a divine power center , '' Mangal Chaudhary , the head priest of the Gadhimai temple , said by phone . `` When people wish for a son , a job , good health or anything else come true , they make an offering to the Gadhimai goddess . ''

He expects more than 5 million people -- 60 percent from India , which shares an open border with Nepal -- to attend the festival .

About 15,000 male water buffalo will be slaughtered , up from 12,000 five years ago , said Chaudhary , who is the 10th generation of his family to serve as chief priest .

Water buffalo are slaughtered on the first day , and other animals on the second day .

Government officials say they can not stop the centuries-old tradition , despite opposition from animal-rights activists from Nepal and India .

`` This is a matter of people 's religion and belief , '' said chief district officer Tara Nath Gautam , the highest-ranking government official in Bara .

Animal rights activists say they are n't looking for a sea change .

`` We do not expect this practice to stop overnight . A sustained effort is needed so that , sometime , the practice will end , '' said Nepali animal rights activist Pramada Shah .

Though meat from the sacrificed animals is given to devotees , the hides of water buffalo are taken by the festival management committee to sell . The heads are buried on the temple premises , which spread over three square kilometers , Chaudhary said .

Buffalo is eaten by low castes in Nepal and India , but goat meat is eaten by a wider population .

An estimated 100,000 to 200,000 goats are sacrificed , Chaudhary said .

Journalist Manesh Shrestha contributed to this report .

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About 200,000 animals , including male water buffalo , goats and roosters will be slaughtered over two days

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Animals are sacrificed to the goddess Gadhimai in thanks for wishes granted

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Government officials say they can not stop the centuries-old tradition , despite opposition

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Animal-rights activists says they do n't expect the practice to end overnight but change is needed